“Failed to open input stream in remixing stream”

Not sure what I’m doing wrong, but this error started appearing last week and now I can’t play anything on my Apple TV. The files are playable from my iPad and iPhone just fine.

Any ideas? I’d provide more information if I knew what might be going wrong, but I really don’t.

trying to click into my folders says “error occurred username and password incorrect”, but then I have iCloud sync turned on, so surely the fact it works on my iPad, should mean it works on the Apple TV?

Thank you